Multiple mac mini built using same image

I have trying to connect multiple mac computers which were build using the Apples migration assistant. Essentially the macs are duplicates from an image. When adding a duplicated mac however to realVNC, realVNC however will not uniquely identify the duplicate mac from original unit where the image was sourced. The duplicates will join with same signature code. Logging in from realVNC will randomly connect to any of the macs.

1. How can I update the duplicated macs so that they are unique to realVNC? What parameter in the machine does realVNC gets the Signature Code?

2. What do you recommend to solve this issue?